Heterojunction of CuO nanoclusters with TiO₂ for photo-oxidation of organic compounds and for hydrogen production

Heterojunctions of small CuO nanoclusters (synthesized by radiolysis) with TiO₂ (commercial P25) induced a photocatalytic activity under visible light irradiation in a wide range of wavelengths due to the narrow bandgap of CuO nanoclusters of around 1.7 eV. The optical, chemical, and electrical properties of these composite nanomaterials were studied. The photocatalytic properties of bare and modified TiO₂–P25 were studied for water purification (photooxidation of organic compounds such as phenol and 2-propanol) and for hydrogen generation under visible light irradiation. Time resolved microwave conductivity signals showed activation of TiO₂ under visible light, proving the injection of electrons from CuO nanoclusters to the conduction band of TiO₂–P25. The modified materials showed high photocatalytic activity under visible light. The important role of charge-carriers was demonstrated for both photoreduction and photooxidation reactions.